1. Field of the Invention
The present invention generally relates to a lock-up damper. More specifically, the present invention relates to a lock-up damper used in a fluid torque transmission.
2. Background Information
One known example of a fluid torque transmission is a torque converter equipped with a lock-up device. A lock-up device is a mechanism for mechanically linking a front cover and a turbine, and is disposed in the space between the turbine and the front cover. The lock-up device directly transmits torque from the front cover to the turbine.
A conventional lock-up device has a piston and a lock-up damper. The piston is disposed movably in the axial direction, and slides with the front cover when pressed against the front cover. The lock-up damper has a pair of input members, an intermediate member, a pair of output members, a plurality of first springs that elastically link the pair of input members and a hub flange in the rotational direction, and a plurality of second springs that elastically link the pair of output members and the hub flange in the rotational direction. The pair of input members support the first springs so that they are capable of elastic deformation in the rotational direction, and rotate integrally with the piston. The pair of output members support the second springs so that they are capable of elastic deformation in the rotational direction, and are fixed to a turbine hub. In between the input members and the output members, an intermediate plate functions as an intermediate member that acts on the first and second springs in series.
When the piston is pressed against the front cover by hydraulic pressure, the torque inputted to the front cover is transmitted to the turbine via the piston and the lock-up damper. At this point torsional vibration is absorbed and attenuated by the lock-up damper (see Japanese Laid-Open Patent Application S61-252964, for example).
With a conventional lock-up damper, however, a pin and a slot were employed as a stopper mechanism that restricted the relative rotation of the intermediate plate and the output plate, and the pin was disposed between the second springs in the rotational direction. Therefore, a large maximum value of the relative rotational angle of the intermediate plate and the output plate could not be ensured, and this adversely affected the design latitude of the lock-up damper.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved lock-up damper. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.